Dual Gridded Reflector (DGR) antennas are widely used in satellite communication systems. DGR antenna systems consist of two reflecting surfaces (i.e., shells), one in front of the other. The front shell is gridded, reflecting a linearly polarized electromagnetic wave, while allowing an orthogonal linearly polarized electromagnetic wave to pass through. Using this arrangement, DGR antenna systems are able to reflect two beams of electromagnetic waves having orthogonal linear polarizations. DGR systems are able to achieve low cross-polarization isolation between two orthogonally polarized beams—i.e., interference between a first beam and an orthogonally polarized second beam—and are, therefore, said to have high-cross polarization purity.
Conventional DGR antenna systems have supporting structural elements to keep the two reflective surfaces in the desired position relative to each other. These supporting structural elements would perturb the incoming and outgoing orthogonally polarized electromagnetic waves, causing deformation of the radiation patterns with additional high level of side-lobes. Such additional side-lobes are highly undesirable, especially in geographic regions where high-level isolation in the transmit and receive operating frequency bands is required.